Recently, research has been actively conducted in regard to an insulator which is formed of an oxide such as VO2 or a compound including holes such as GaAs and in which resistance variations occur due to an external voltage. In particular, experimental research has been performed in order to find a cause of transition in a discontinuous MIT material in which an abrupt transition occurs from an insulator to a metal.
The MIT material is formed on a substrate and then forms an electrode so that the MIT material may be used to form an MIT device having two or three terminals. Such an MIT device may be applied to various electronic devices. For example, a field effect transistor (FET) using an MIT material is disclosed in U.S. Pat. No. 6,624,463 B2 (Sep. 23, 2003).
In the MIT material or the MIT device including the MIT material, if a voltage applied to the MIT device is equal to or greater than a predetermined voltage (hereinafter referred to as a transition voltage), a current is discontinuously and abruptly increased or a resistance is discontinuously and abruptly decreased, and a transition occurs from an insulator state to a metal state.
In general, such an MIT material is formed of an oxide or a compound including holes. However, in the MIT material formed of two or more elements, an undesired second phase transition may occur after an MIT occurs.